public class five {
    public static void main(String[] args) {
        //计算分数的值
        double count=0;
        for(double i=1;i<=100;i++){
            if(i%2==1) {
                count=count+1/i;
            }else{
                count=count-1/i;
            }
        }
        System.out.println(count);
    }
}
